(a) Technical Field
The present disclosure relates, generally, to a battery pack. More particularly, the present invention relates to a battery pack having cell assemblies, each of which preferably contains unit cells therein.
(b) Background
Environment friendly electric vehicles, such as fuel cell vehicles or hybrid electric vehicles, are preferably equipped with batteries for suitably supplying electricity to various high-voltage parts including a drive motor. Preferably, each battery includes a plurality of unit cells, which are secondary cells, and that repeat charge/discharge during operation of the vehicle, and suitably supply electricity to high-voltage parts of the vehicle.
A typical high-voltage battery for the fuel cell vehicles supplies electricity both to elements (e.g. a blower) of a fuel cell system and to a variety of high-voltage parts, and suitably stores electricity that is generated by fuel cells or by a drive motor (during a regenerative braking mode).
In general, a typical high-voltage battery for the hybrid electric vehicles supplies electricity to a variety of high-voltage parts, such as a drive motor, and suitably stores electricity generated by the drive motor.
Preferably, each battery, which is suitably mounted on the electric vehicles and is used as chargeable/dischargeable electricity accumulating means, is provided in the form of a battery pack. Further, the battery pack is preferably configured to receive a plurality of cells in a case to suitably form a cell cartridge (or a cell assembly), modularize the cell cartridge and thereby form a unit module, and suitably stack a plurality of unit modules.
Preferably, this vehicle battery pack is subject to an increase in temperature which occurs during use, so that the battery pack is preferably designed with ventilation and cooling taken into consideration. When the temperature of the battery pack is suitably increased, charge/discharge efficiency thereof is suitably reduced. Further, when the temperatures of the cells of the battery pack are out of balance, the life span of the cells is suitably reduced. Accordingly, it is necessary to provide a technique for suitably maintaining the temperature of the battery pack within a range where the battery pack can produce optimal performance, by arranging the cell cartridges at appropriate intervals.
Preferably, in this battery pack, each cell cartridge is suitably configured to stack a plurality of cells in a cell case, and each unit module is suitably configured to stack the cell cartridges in a module case so as to be spaced apart from each other. Then, the unit modules are stacked.
Preferably, it is further required to secure a cooling passage for the cells received in each cell cartridge. Accordingly, the cell cartridges are suitably assembled spaced apart from each other using a specific part.
Preferably, the case used for holding the cells in respective cell cartridges includes a first outer frame, a middle frame and a second outer frame. To form the cooling passages into a unit module, the cell cartridges are suitably installed in the unit module such that the unit cells are interposed between the first outer frame and the middle frame and between the middle frame and the second outer frame.
Preferably, when cell cartridges are fabricated into a unit module, it is may be further required to define the cooling passages between the cell cartridges in the unit module, so that, in the prior art, separators are further required for spacing the cell cartridges from each other. However, the use of the separators in the unit module increases the volume of the unit module and the volume of the battery pack.
Further, because the conventional battery pack must be provided with the middle frame for reinforcing the strength at positions between the unit cells, the conventional battery pack has an increased volume of the cell cartridges, an increased volume of the unit modules and an increased volume of the battery pack, the battery pack has a complicated structure, and furthermore the number of parts and the production cost thereof are increased.
Accordingly, in the conventional battery pack, it is considerably difficult to directly produce a battery pack using the cell cartridges, but it is required to fabricate the cell cartridges into a unit module.
Accordingly, to produce the conventional battery pack, a plurality of unit cells (typically, a pair of unit cells) are suitably assembled with a frame, thus forming one cell cartridge. Further, a plurality of cell cartridges are produced in the same manner and the cell cartridges are fabricated into a unit module. A plurality of unit modules are stacked, thus producing a battery pack. Accordingly, the conventional battery pack is suitably produced through many processes. Accordingly, assembling efficiency and productivity are suitably reduced, and assembly time, the number of processes, and the cost of production are suitably increased.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.